The objective of the proposed work is to understand the critical biochemical steps in the mechanisms of transfection and transfection enhancement. Enhancement of transfection in B. subtilis bears similarities to the SOS repair process in E. coli in certain respects. It results in an increase in the efficiency of DNA rescue in transfectant cells and it is induced by ultra-violet light in a process that requires protein synthesis. A mutant has been isolated which is constituitive for the enhanced transfection. This mutant appears to be lower than other strains in the level of activity of one (or more) enzymes which solubilize single stranded DNA. As initially isolated, the mutant was also very depressed in the level of transformation. However, recent studies show that most of the depression in transformation can be attributed to an unlinked mutation which is easily separable from the mutation responsible for the constituitive enhancement. Nevertheless, the constituitively enhanced mutant does show less transformation, about 30% of the normal value, and the role of this gene in binding and uptake of both transfecting and transforming DNA will be examined. Enzymatic studies to examine the levels of nucleases in the segregants from the original constituitive mutant are in progress which should permit a determination of the role of nucleases in the enhancement process. In addition, the protein pattern of normal and ultra-violet induced bacteria in two dimensional electrophoresis has been determined and studies are in progress to relate these changes to the changes seen in the constituitively enhanced mutant and other mutants which are defective in achieving normal competence.